In recent years, there is a trend to advance digitization of information, and an image processing apparatus such as a printer and a facsimile used for outputting digitized information as well as a scanner used for digitizing a document has become an essential apparatus. In such image processing apparatus, reduction of power consumption during non-operating time of the apparatus has been sought after, and there has been used control of a power-saving state in which power supply to a part of the apparatus is stopped.
As an aspect of such control of the power-saving state, there has been proposed a technique of enabling communication with a host PC while reducing the power consumption (see, for example, Patent Literature 1). In this technique, even in an energy-saving mode that achieves specified power consumption, power is supplied to an application specific integrated circuit (ASIC) installed with an interface (I/F) for connecting with the host PC and, by using the ASIC, the communication with the host PC is performed.